Renal anemia refers to anemia caused by insufficient production of erythropoietin (EPO) in the kidneys due to various factors or some toxic substances in uremic plasma interfering with the production and metabolism of red blood cells. Although recent research progress has shown that the kidneys are closely related to the production of red blood cells, there is still some controversy about the pathogenesis of renal anemia. It is generally believed that the occurrence of renal anemia is caused by a combination of multiple factors. When azotemia occurs in severe kidney disease, anemia is often present. The degree of anemia has a certain parallel relationship with azotemia. Generally, anemia begins to occur when the glomerular filtration rate drops to 25% to 30% of the normal level. Clinically, renal anemia can be divided into renal anemia with normal renal function and renal anemia caused by chronic renal failure. The latter is more common and is also one of the important causes of secondary anemia.